Mangiferin prevents myocardial infarction-induced apoptosis and heart failure in mice by activating the Sirt1/FoxO3a pathway.

Myocardial infarction (MI) commonly leads to cardiomyocyte apoptosis and heart failure. Mangiferin is a natural glucosylxanthone extracted from mango fruits and leaves, which has anti-apoptotic and anti-inflammatory properties in experimental cardiovascular diseases. In the present study, we investigated the role and detailed mechanism of mangiferin in MI. We used ligation of the left anterior descending coronary artery to establish an MI model in vivo, and cardiomyocyte-specific Sirt1 knockout mice were used to identify the mechanism of mangiferin. For in vitro studies, oxygen and glucose deprivation (OGD) was used to mimic ischaemia in H9c2 cardiomyocytes. In mice, mangiferin treatment increased Sirt1 expression after MI, significantly reduced the infarct area, and prevented MI-induced apoptosis and heart failure. Mangiferin reduced OGD-induced cellular apoptosis in H9c2 cells. Meanwhile, Sirt1 knockout/silencing abolished the protective effects of mangiferin. Further studies revealed that mangiferin increased FoxO3a deacetylation by up-regulating Sirt1, thus preventing apoptosis, and adenovirus-mediated constitutive acetylation of FoxO3a restricted the anti-apoptotic effects of mangiferin in vivo and in vitro. Our results indicate that mangiferin prevents cardiomyocyte apoptosis and the subsequent heart failure by activating the Sirt1/FoxO3a pathway in MI, and suggest that mangiferin may have an interesting potential in following studies towards clinical evaluation.

Bioequivalence Study of Two Formulations of Mifepristone Tablets in Healthy Chinese Subjects Under Fasting Conditions.

A single-dose, open-label, randomized, two-period crossover-design study was conducted to evaluate the bioequivalence of the reference and test formulations of mifepristone tablets. Each subject was randomized at the beginning to receive a 25-mg tablet of the test or the reference mifepristone under fasting conditions during the first period, then received the alternate formulation during the second period following a 2-week washout period. A validated high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was used to determine the plasma concentrations of mifepristone and its two metabolites (RU42633 and RU42698). Fifty-two healthy subjects were enrolled in this trial, 50 of whom completed the study. The 90% confidence intervals for the log-transformed Cmax , AUC0-t , and AUC0-∞ fell within the accepted 80%-125% range. Throughout the study period, a total of 58 treatment-emergent adverse events were reported. No serious adverse event was observed. In conclusion, the test and reference mifepristone were bioequivalent and well tolerated under fasting conditions.

The protective effects of fibroblast growth factor 10 against hepatic ischemia-reperfusion injury in mice.

Hepatic ischemia-reperfusion injury (IRI) is a major complication of liver surgery and transplantation. IRI leads to hepatic parenchymal cell death, resulting in liver failure, and lacks effective therapeutic approaches. Fibroblast growth factor 10 (FGF10) is a paracrine factor which is well-characterized with respect to its pro-proliferative effects during embryonic liver development and liver regeneration, but its role in hepatic IRI remains unknown. In this study, we investigated the role of FGF10 in liver IRI and identified signaling pathways regulated by FGF10. In a mouse model of warm liver IRI, FGF10 was highly expressed during the reperfusion phase. In vitro experiments demonstrated that FGF10 was primarily secreted by hepatic stellate cells and acted on hepatocytes. The role of FGF10 in liver IRI was further examined using adeno-associated virus-mediated gene silencing and overexpression. Overexpression of FGF10 alleviated liver dysfunction, reduced necrosis and inflammation, and protected hepatocytes from apoptosis in the early acute injury phase of IRI. Furthermore, in the late phase of IRI, FGF10 overexpression also promoted hepatocyte proliferation. Meanwhile, gene silencing of FGF10 had the opposite effect. Further studies revealed that overexpression of FGF10 activated nuclear factor-erythroid 2-related factor 2 (NRF2) and decreased oxidative stress, mainly through activation of the phosphatidylinositol-3-kinase/AKT pathway, and the protective effects of FGF10 overexpression were largely abrogated in NRF2 knockout mice. These results demonstrate the protective effects of FGF10 in liver IRI, and reveal the important role of NRF2 in FGF10-mediated hepatic protection during IRI.

Metallothionein Protects the Heart Against Myocardial Infarction via the mTORC2/FoxO3a/Bim Pathway.

Aims: Cardiac-specific overexpression of metallothionein (MT) has been shown to be beneficial in ischemic heart disease, but the detailed mechanisms through which MT protects against myocardial infarction (MI) remain unknown. This study assessed the involvement of the mTORC2/FoxO3a/Bim pathway in the cardioprotective effects of MT. Results: MI was induced in wild-type (FVB) mice and in cardiac-specific MT-overexpressing transgenic (MT-TG) mice by ligation of the left anterior descending (LAD) coronary artery. Cardiac function was better; infarct size and cardiomyocyte apoptosis were lower in MT-TG mice than in FVB mice after MI. Moreover, MT-TG mice exhibited better phenotypes after LAD ligation than FVB mice treated with Mn(III)tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (MnTMPyP; a reactive oxygen species [ROS] scavenger) and cardiac-specific catalase-overexpressing transgenic (CAT-TG) mice, which showed the same ROS levels as MT-TG mice after MI. Activation of mechanistic target of rapamycin complex 2 (mTORC2) was essential for the cardioprotective effects of MT against MI. In addition, MT attenuated the downregulation of phospho-FoxO3a after MI, inhibiting the expression of the apoptosis-associated gene Bim, located downstream of FoxO3a, and reducing the level of apoptosis after MI. To mimic ischemic-injured FVB and MT-TG mice in vitro, H9c2 and MT-overexpressing H9c2 (H9c2MT7) cardiomyocytes were subjected to oxygen and glucose deprivation, with the results being consistent with those obtained in vivo. Innovation and Conclusion: The cardioprotective effects of MT against MI are not entirely dependent upon its ability to eliminate ROS. Rather, MT overexpression mostly protects against MI through the mTORC2-FoxO3a-Bim pathway.

Fibroblast growth factor 21 protects the heart from angiotensin II-induced cardiac hypertrophy and dysfunction via SIRT1.

AIMS: This study investigated the mechanism through which fibroblast growth factor 21 (FGF21) protects against angiotensin II (Ang II)-induced cardiac hypertrophy and dysfunction. METHODS: Male silent information regulator 1 (SIRT1) flox/flox and cardiomyocyte-specific inducible SIRT1 knockout mice (SIRT1-iKO) were generated and treated with Ang II (1.1 mg/kg/day for 4 weeks) at the age of 8-12-week-old. FGF21 treatment [2.5 mg/kg/day for 4 weeks by intraperitoneal (i.p.) injection] was initiated at the same time as the Ang II infusion. For in vitro studies, neonatal rat cardiomyocytes (NRCMs), H9c2 rat cardiomyocytes and isolated adult mouse cardiomyocytes were treated with Ang II (1 µM) and FGF21 (20 nM) for 24 h with or without SIRT1 silencing. RESULTS: FGF21 treatment significantly attenuated Ang II-induced cardiac hypertrophy and dysfunction. SIRT1 knockout abolished the ability of FGF21 to prevent Ang II-induced cardiac hypertrophy, fibrosis, and apoptosis, without affecting the beneficial effects of FGF21 in Ang II-induced hypertension, and did not influence the hypertension itself. FGF21 markedly increased the deacetylase activity of SIRT1 and promoted the interaction of SIRT1 with liver kinase B1 (LKB1) and forkhead box protein O1 (FoxO1), resulting in decreased acetylation of these SIRT1 target proteins. Consequently, FGF21 promoted the activation of the LKB1 target adenosine monophosphate-activated protein kinase (AMPK) and altered the transcriptional activity of FoxO1 on its downstream target genes catalase (Cat), MnSOD (Sod2), and Bim, resulting in reduced reactive oxygen species (ROS) accumulation and cardiomyocyte apoptosis. CONCLUSIONS: FGF21 improves cardiac function and alleviates Ang II-induced cardiac hypertrophy in a SIRT1-dependent manner.